Optical comparator for testing cams



p 1950 R. o. BEARDSLEY ETAL 2,521,820

OPTICAL COMPARATOR FOR TESTING CAMS 3 Sheets-Sheet 1 p 1950 R. o. BEARDSLEY ETAL 2,521,820

OPTICAL COMPARATOR FOR TESTING CAMS Filed Nov. 14, 1946 3 Sheets-Sheet 2 Sept. 12, 1950 R. o. BEQRDSLEY ETAL 2,521,820

OPTICAL COMPARATOR FOR TESTING CAMS Filed Nov. 14, 1946 3 Sheets-Sheet 3 Patented Sept. 12, 1950 D] STATE PATENT Q Y OPTICAL COMPARATOR FOB.:IESTINGCAMS Robert 0. Beardsley and eon-fie: Fuller, stringfield, Vt., assignors to J ones & Lamson Machine Company, Springfield, Vt.,"a. corporation of Vermont i Application November 14, 94c, Serial No. 709,712

9 Claims.

This invention relates to improvements in comparators. for the purpose of facilitating the testing of cams such, for example, as are on the cam shaft of an automobile motor. It is an object of the invention to provide a comparator of for supporting the Work to be inspected. -A carriage iffl is slidably mounted on the base 28 and is adapted to be moved transverselyaby opera tionofa hand'whee1f32at the front of the c'omparator, this hand wheel b eing mounted on'a shaft 3-; on the other end of which is a pinion 36 the general type described and illustrated in which meshes with a rack 38 secured to the car- Patent No. 1,703,933, granted to Hartness and riage 303. From the front edge of the carriage Porter on March 5, 1929, with improvements dea bracket 48 projects up and over the table 22.

. signed to adapt the mechanism particularly for At; the; upper end of this bracket is a vertically easy and accurate testing of vertical distances l adjustable head 4?. which is dove-tailed to the from a horizontalline or plane of reference which bracket and is secured in adjusted; positionby a is definitely located with respect to the fixed -,setsc rew 43., A feelergauge member 44 runs on worktable of thecomparator. For example, the 1 ball bearings 4 6; whichare vertically arranged in comparator hereinafter-described isdesigned for the head fizand are adjusted so ,thatth'el vertical checking on the radial distances of cam surfaces movementsof the gauge are free but lateral play .from the axis of the cam shaft on which the is substantially;eliminatedygwedged into,a"'ta- I cams are fixed, the cam shaft being mounted pered bore in the lower end of thei'member'c i is over the'work table with its axis definitely loa cont act piece 48 which is in'the shape ofian cated with reference to the work table. 3 For automobile motor tappet when the comparator is this purpose, a feeler gauge is mounted over the vto loe tis -z d for testing cams on the cam shaft of work table to bear on a cam and to cast a shadow an automobile motor. The contact piece'48 thus image on the screen, the structure being arengages thecam W injust the same manner as ranged so that the contour of the'shadow on the i thecameis engaged by a tappet when it'is in'place screen indicates the vertical distance of the point as a part of automobile motor. At the upper o i of contact on the cam above the axis of the cam cndgof the membjer 4451s a reference indicator shaft. 1 t w fill hayingone; edge serrated with a' succession of For-a more complete understanding of the inhorizontal knife edges 52 spaced. apar-tibyedual vention, reference may be had to the following verticaldistances For exampla thefspace bedescription thereof, and to the drawings; of tween successive knife edges EZ m'a y conveniently hich; p H 30, be onetenth ofan-inch. When the comparator Figure 1 is an end elevation, of a comparator isin use alight beamis cast across this serrated embodying the invention; portions being broken edge so as to project a shadow image of "a poraway; tionthereof on a screenvas hereinafter described.

Figure 2 is a section on the line 2--2 of Fig- Since the bracket 4 B; which supports the feeler ure 1; v gauge is fixed on the: carriage 3i], it is evident Figure 3 is a front elevation of the comparator thatthegauge may-be shifted, from side topside shownin Figure 1'; with the ;:carriage. 30;,by rotation, ofqthe ghand Figured is a section on the line 4-4 ofFigwheel t fiso as to bring 'it dir ectl y over anyseure 3; I 1 jlEQtQd tine-{Of a nurnber oi camsLW Omashaft Figure 5 is a section on the line 5-i-5 of Fig- 40. supported between. {the ;headstock 24-and;,tailure 4; i stock-:26; Lateral shifting of the gauge may-"also Figure 6 is a section on the line 6-6 of Fig- -be employed to check up on the angle which the urel; edge: of the cam makes with the axis of the cam Figure 7 is a section on the line 1-! of Figshaft, Cam edges of thiskind are oftenslightly Y ure 6; inclined with respect tothe shaft axis so that Figure 8 is a front elevation of the chart and cnii u t y Wi l tend impart avgladllal its supporting structure; rotating motion to -t the tappet sovas to distribute Figure 9 is a section on the line 9-9 of Fig- W 11th? e p e I j 5 e 8, I t Also mounted onthe-oarriage 30 is a structure The comparator illustrated on the drawings Which is hinged-15017116 c i ge; so that the strucis for testing cams on aV-cam shaft and is proture may b ro ab r z ntal a iS- tvided with a base to having at the front thereof This rockable s ruc ur comprises a housing 60 a work table 22., On the work table are adjusthaving'a rear wallon which is secured a U-shaped ably mounted a headstock 24 and a tailstock 26 bracket 62. -'Ihis bracket is provided with pivot elements (Figure-6): which engage in horizon- *"tw'eeiitpe a ms-draw -=s a'sti t' shart mo fitted-in one or uie standards'tii syrotationbf the headwlieel92fthe housings: andf'a'lh'off the etherjmeiiibers associated therewit-h may be shifted for'ward'iorbackas'the shaft ea rot ates' in the ut ss fsigui s 1 ance'suew "tlie'stub s'haft we coaxialwiththepivotnieiiibers" so that it rocks about the rocking axis whichis near the rear thereof. 7 The slots 66 for pivot elements 64 are to permit forward and rearward adjustment of the rockable structure as hereinafter described.

The rockable structure which includes the housing 60 also includes a horizontal frame member 16 on which is adjustably mounted a standard 18 supporting a mirror Bil. The standard 18 and mirror 80 are adjustable forward and rearward to vary the degree of magnification of the shadow image cast on the screen as hereinafter "described. A set of stops are carried by a sup- 1 port '8! to be used selectively in connection with the slidable standard 18 to locate the mirror at any one of a number of predetermined positions on the member 16, as described and illustrated in Patent No; 2,222,165, granted to Beardsley and Finn on November 19, 1940. The frontwall of the housing supports a projecting lens system 82- through which a beamof light may be directed 'from a lamp housing mounted on a forward extension 86 of the frame It so that the lamp housingis also a part of the rockable structure. Mounted in the upper front wall of the housing '60'is a rectangular frame 88 which contains a translucent screen or chart 90: The optical system of the comparator consists of a source of light within the lamp house 84 which also contains a condensing lens (not shown) for the pro-- jection of horizontal beam of light from the lamp housing into the lens system 82. This beam is projected past the serrated edge of the gauge'member 50 so that a magnified shadow image of the serrated edge 52 is refiectedby the j mirror-50' to the screen 90. When the'feeler gauge engages a cam W, the gaugeis displaced upward according to the radial distance of the j'point of contact from the axis of the cam. Hence the elevation of the gauge element 50 is a measure 1 of such radialdimension-of the cam. In order to accommodate cams of different radialdimensions; it: is sometimes necessary to elevate the op- For this purb'een' rocked, to sharpen the focus. For this purj pose, a hand wheel92is mounted on a shaft 94 f'which is journalled at its forward end in the front "wall of the housing 80. The rear end portion of the'shaft 9dis screw threaded and engages in a nut 9a (Figure 6 This 'nut is te fitted beed -blo dk-sa' whicn has 4 B4. If the hand wheel 92 is operated to shift the rockable structure forward or rearward from such position, the stub shaft will then be out of line with the pivot members 64. In order then to avoid binding of the pivot members when the house is tilted, the arms of the block 98 have oval apertures I02 through which the shaft 94 extends, thus permitting the nut 96 to adjust itself vertically a limited but sufficient distance.

Figure 8 shows the screen '36 on which a shadow imageof a portion of the serrated edge 52 is "east, "such shadow image being preferably of 1 somewhat more than the vertical length between successive horizontal edges. The optical system is preferably such that the magnification is 100 times. That means that in the particular apparatus illustrated the vertical distance between the shadow images of consecutive horizontal edges of the -serrated edge 52 is inches. The screen 90 is in two parts 1M -"and H16, these parts being divided by a vertical median line [68 which is the boundary between the abutting edges of the two parts of the screen." Scale divisions are printed or otherwise made on the two parts of the chart on either side of the median line I08, thesescale divisions being equally spaced apart by distances equal to a predetermined fraction of the distance between the shadow images of successive horiz'ontal edges. As shown-in Figures 8, the .10 inch vertical distance between edges is preferably divided into 160 equal parts by the scale divisions on the sections of the chart. One of these sections, section 5156 for "exampleds vertically mov- 1 Cable with respect to the other-section. v For this purpose, the section 106 is -mounted 'on' afra'me member lid-which is'secured to a bar'll 2. This "bar is movably mounted on ball bearings I I-3'in a side'membe'r of the frame 88. On the frame mem- 'b'er H0 is mounted an abutment bracket i M hav- Q ing an opposing anvil H6 projecting downward to engage the end of a micrometer anvil H8.

The latteran'vil is axially adjustable by means of 'a micrometer screw mechanism having a finger "knob l2il' which is rotatable and which is sup- -ported by'a bracket I22 fixed on a side member of the frame 88-. The periphery of the finger knob "$28 is preferably provided withscale marks which arecalibra'ted with reference to the pitch of the 'screw which moves the rod .1 18 so that each scale division on the finger knob represents axpres'determined fraction of a. scale division on the '-chart 90; For example, in the mechanism 'illustrated on the drawings, if the finger knob P20 is turned sovthat l0 scale marks pass the-index,

the movable portion 196 of the chart will travel up or down a-distance equal to one scale division on the chart. Thus, if the shadow image of :a ahorizontal-edg'e falls between scale divisions on the chart, the finger knob 20 may be rotatedsufficiently to bring cheer the scale. divisionson the movable portion 96 into exact registry with the "shadow image; If the comparator is properly'adjusted, the radial dimension of the cam which-is "being tested canthen be read from the scale on the fixed portion of the chart and the scale on the finger knob 12!].

In order to determine the rate of lift of a tappet bya -camdt is desirable to measure and tabulate the lift of the tappet for each degree mof rotation of 13118021111." For this purpose'the headstock 24 is preferably provided with indexing -n'1'eanswhich may include a wheel I38 having scale'divisions on its rim indicating'degrees of angle; this wheel being mounted on a'spindle I32 7 journalled intheheadstock. [For slow motion r, 1 rotation'of thewheel, an ordinary worm and gear for successive degrees of angular change of the cam, and the values thus obtained may be plotted 1 to form'a'graph.

We-claim: l

1.- Ina -comparator-having a base and a stationary work table thereon, a carriage laterally slidable onsaid base, means operable to adjust said carriage laterally, a gauge mounted on said carriage over said work table, a structure pivotally mounted on said carriage and adjustably rockable as a unit about a horizontal axis, said structure includin a lamp stand in front of the work table, a housing behind the work table, a screen mounted on the forward portion of said housing and a lens system and mirror in said housing, means operable to rock said structure about its axis, and means operable to shift said structure forward and rearward.

2. In a comparator having a base and a stationary work table thereon, a carriage laterally slidable on said base, means operable to adjust said carriage laterally, a gauge mounted on said carriage in position to engage a work piece on said table, a structure including a lamp stand in front of said work table, a housing behind the work table, a screen mounted on the forward portion of the housing and a lens system and mirror in said housing, said structure being hinged to said carriage near the rear thereof and adjustably supported on the carriage near the front thereof, and means for adjustably rocking said structure about its hinge axis.

3. In a comparator having a base and a stationary work table thereon, a structure carried by said base including a lamp stand in front of said table, a housing behind said table, a screen mounted in the front wallof said housing, and a lens system and mirror in said housing arranged to receive a light beam from a lamp on said stand and to project the same on said screen, said structure being pivotally connected to said base near the rear thereof and being adjustably supported near the front thereof, and means for adj ustably rocking said structure about its pivot axis.

4. In a comparator having a base and a stationary work table thereon, a carriage laterally slidable on said base, means operable to adjust said carriage laterally, a feeler gauge mounted on said carriage over said work table to engage different parts of a work piec on said table when the carriage is laterally shifted, a lamp stand mounted on said carriage in front of said table, a frame hinged to said carriage, a lens system and screen mounted on said frame behind said table, said lamp, lens system and screen being arranged so that a shadow image of a portion of said gauge is cast on said screen, means operable to rock said frame through a limited angle about its hinge axis, and means for shifting said frame forward and rearward independently of its angular position.

5. A comparator for testing cams on a cam shaft or the like, comprising a base, a work table mounted on said base, means on said table for supporting a cam shaft with its axis horizontal, a carriage movable on said base in a direction parallel to the axis of a shaft supported on said table, a feeler gauge supported above said shaft and vertically movable to bear against one of ,fsaidcains, af' bra'cket on said carriage for supporting said feeler gauge, and means mounted "on said carriage for forming amagnified shadow image of 'a portion Of said feeler gauge'ysa'id I means and feeler gauge being movable as a unit with said carriage to bring thefeelergauge into positionto bear on any selected cam 'on' said shaftwithout' disturbing the relativeadj-ustm'ent between the parts of said means and said feeler 6. A comparator-"for testing cams on a cam shaft or the like, comprising abase, a stationary work table on said base, means on said table for -'-'supporting* a-cam shaft and cams; a-carriage laterally movable on said base,a bracket'mounted on said carriage and extending over said table, a vertically movable feeler gauge mounted on said bracket and adapted to bear against a cam on said shaft, the upper portion of said feeler gauge having a vertically spaced series of horizontal edges equal distances apart, and an optical system mounted. on said carriage and comprising a light source in front of the work table, means for projecting a beam of horizontal parallel rays from said light source against said upper portion of the feeler, a translucent screen, and means for magnifying the shadow image of a portion of said gauge and focussing the same on said screen, said bracket, light source and optical system being movable as a unit with said carriage to bring said feeler gauge into position for engagement with any selected cam on said cam shaft.

'7. In a comparator for testing cams on a cam shaft or the like, means for supporting a cam shaft with its axis horizontal, a feeler gauge having a lower portion shaped like a tappet and an upper portion with vertically spaced horizontal edges, means for supporting said feeler gauge over said shaft so that said lower portion bears on a camto be tested, a screen having reference marks thereon, means for casting a magnified shadow image of a portion of said gauge on said screen for comparison with said reference marks, and means for moving said gauge, screen and shadow casting means as a unit in a direction parallel to the axis of said shaft to bring said feeler into position for engagement with any selected cam on said shaft.

8. In a comparator, in combination, a screen, a feeler gauge having vertically spaced horizontal edges and means for casting on said screen a magnified shadow image of a portion of said gauge, said screen having two relatively movable parts defined by the vertical median, scale marks on one said parts equally spaced apart by distances equal to a predetermined fraction of the distance between the shadow outlines of two successive horizontal edges of the gauge, similarly spaced scale marks on the other part of said chart adjacent to said median, means including a screw and a handwheel thereon for adjustably shifting one of said parts relatively to the other, and scale marks on said wheel for indicating relative movements of said parts equivalent to predetermined fractions of one scale division on.

said chart.

9. A comparator for testing cams on a shaft or the like, comprising a base, a stationary work table on said base, means on said table for supporting a cam shaft with cams, indexing means on said table for facilitating step by step rotation of the shaft to successive predetermined angular positions for testing corresponding cam measurements, a feeler gauge supported by said base over 

